For many years, beds have been composed of resilient or spring bases on which are placed mattresses composed primarily of fabric envelopes containing soft, spongy innards. In some instances, the base (hereinafter referred to as box-spring) and mattress have been combined; in others, the box-spring has been eliminated and the mattress placed on a firm, unyielding surface.
The use of cots, as a temporary expedient, essentially embodied the principles of the aforementioned and more traditional bed/bedding structures. But, since cots are for only temporary setup and cannot (because they are constructed for limited purposes) be generally employed for orthopedic prescriptive means, they shall no longer be considered as falling within the subject genre.
Floatation sleeping apparatus, namely the waterbed, has successfully provided orthopedic support means and is utilized by many whose requirements cannot be successfully accommodated by the traditional box-spring and/or mattress. But, flotation equipment is often heavy, bulky and relatively immobile. It requires special water treatment, as well as heating means and water-escape prevention mechanisms.
Retreating to the traditional box-spring and mattress then, as a means of providing prescriptive orthopedic therapy, we are faced with their inherent defects and disadvantages. The standard bed has employed springs for decades. The spring gives a constant rate of loading under increasing stress. Therefore, under differing loads the spring will extend or compress to different lengths which, in the assembled device, would equate to different depths of depression. Arbitrarily speaking, a man weighing 400 pounds would compress the spring four inches; whereas, a man weighing 100 pounds would compress it to one inch. This loading characteristic makes the spring ill-suited as a mechanism for orthopedic support where one desires to avoid such linearity.
Another disadvantage to the use of the spring is the high labor cost involved in building a wood frame, placing hundreds of springs in the frame, adding padding to insulate the springs from an outer covering and using an expensive textile fabric to provide the envelope covering the entire structure. Further, no matter how many springs are used, or how closely they are packed, there will be space between them. This condition suggests that the standard bed (boxspring or composite mattress) does not give complete support to the body.
Finally, the volume occupied by the traditional box spring and mattress is quite large. In fact, the larger beds (double, queen-sized, king-sized) are often as immobile and spaceconsuming as flotation beds.
I have devised an orthopedic support structure for use as a bed which clearly avoids the aforementioned disadvantages. First, my invention will provide orthopedic support and can be fabricated to prescription. That is, since an orthopedic bed is to provide a certain degree of supportive therapy, depending upon the weight and mass of the person reposing thereon, it inculcates a variable in its manufacture that may be adjusted to specific situations. Rather than attempting to devise a spring that does not have the usual spring limitations, I have eliminated the spring altogether. Having eliminated the spring, I have eliminated also its bed trappings, i.e., connecting wires or ties, padding and envelope which are so necessary in the construction of a box-spring/mattress. My invention is simple in construction, requires low volume of space, may be easily moved, and has the added advantage of being noiseless when subjected to heavy body weights or undue twisting and turning.
For purposes of clarification, although the instant disclosure will be readily understood by those of ordinary skill in the art, certain definitions shall be established and a brief discussion of certain fibers and their desireability for use in the invention shall be explained.
One of the first terms that the reader will encounter in this disclosure is "heat set" as applied to synthetic fibers. Heat setting is a process by which a certain characteristic is achieved. It is a physical change in a synthetic fiber characterized by the formation of a crystaline region and gives the fabric, of which the fiber is a part, better dimensional stability. By the process, fabric engineers are able to obtain desired stress/strain characteristics for a particular fiber.
Certain fibers of the aforementioned "heat set" class are known as "thermoset" fibers in that they can be repeatedly set and reset according to the aforementioned process. This is achieved by heat setting this type of fiber to a different configuration by subsequent application of temperatures higher than that used to achieve the (first or) previous heat set. The polyesters comprise a generic set of "thermoset" fibers.
"Thermoplastic" fibers, for example Nylon, Lycra and acetate, are fibers that become plastic under certain heat conditions (point of plasticity being the Young's Modulus, wherein the fiber will not return to its original form). For every different fabric, testing has to be done to determine its heat setting conditions. Heat set temperatures commonly used in the textile industry for the fibers under discussion are as follows:
polyester--350 to 425 degrees Farenheit (F) PA0 Nylon 66--400 (F) PA0 Nylon 6--385 (F) PA0 acetate--385 (F) DuPont Corporation's Trademark PA0 Lycra *--385 (F) for polyurethane fiber
Fiber of two entirely different polymers are used in the construction of the invention, one set being polyurethene, and the other set being polyester, polyamide or other synthetic fiber. Polyester fiber is known as "thermoset", while polyurethane, polyamide, polypropylene and acetate are referred to as "thermoplastic". Polyurethane fiber has higher stretch, power and better elasticity characteristics; polyester and polyamide fibers give a fabric better dimensional stability and are less expensive than polyurethane. Thermoplastic fibers are characterized by Nylon (polyamide), Lycra (polyurethane) and cellulose triacetate, a regenerated cellulose fiber, and are generically characterized by the quality that they may be set only once The thermoset fibers are best illustrated by the trademarked products Dacron, Fortrel and Kodel (polyester).
Other terms known to those versed in the art are "weft" and "Warp-knitting" as opposed to "weaving"; all which refer to the method of constructing a fabric. Knitting, using the warp technique, permits higher precision in fabric engineering and gives a better and more balanced stretch in both warp and weft directions Warp-knitting allows higher productivity with the added advantage that the fabric will not fray i.e., the yarn cannot be unravelled at the edges.
The advantages of the invention are set forth in part herein or shall be obvious herefrom and may be learned by practice with the invention.